H8/d9 fit — Loose running fit
ISO 286 hole-basis clearance fit. Enter a nominal size to get the limits.
About H8/d9
Wide clearance on an IT8/IT9 pair for rough-service shafts and bushings where easy running matters more than alignment or finish: agricultural and construction equipment.
At Ø25 mm the hole H8 measures 0 mm to +0.033 mm and the shaft d9 −0.117 mm to −0.065 mm, giving a clearance of 0.065 mm to 0.150 mm.
How the limits are calculated
Hole H8: fundamental deviation EI = 0, standard tolerance IT8 = 33 µm for 18–30 mm. Shaft d9: fundamental deviation es = -65 µm, IT9 = 52 µm. Clearance = hole − shaft, evaluated at both extremes. See the fundamental deviation table for every letter. Values per ISO 286-1:2010.
H8/d9 limits by size range
| Size (mm) | Hole H8 | Shaft d9 | Clearance min | Clearance max |
|---|---|---|---|---|
| ≤ 3 | +0.014 / 0 | −0.020 / −0.045 | +0.020 | +0.059 |
| 3 – 6 | +0.018 / 0 | −0.030 / −0.060 | +0.030 | +0.078 |
| 6 – 10 | +0.022 / 0 | −0.040 / −0.076 | +0.040 | +0.098 |
| 10 – 18 | +0.027 / 0 | −0.050 / −0.093 | +0.050 | +0.120 |
| 18 – 30 | +0.033 / 0 | −0.065 / −0.117 | +0.065 | +0.150 |
| 30 – 50 | +0.039 / 0 | −0.080 / −0.142 | +0.080 | +0.181 |
| 50 – 80 | +0.046 / 0 | −0.100 / −0.174 | +0.100 | +0.220 |
| 80 – 120 | +0.054 / 0 | −0.120 / −0.207 | +0.120 | +0.261 |
| 120 – 180 | +0.063 / 0 | −0.145 / −0.245 | +0.145 | +0.308 |
| 180 – 250 | +0.072 / 0 | −0.170 / −0.285 | +0.170 | +0.357 |
| 250 – 315 | +0.081 / 0 | −0.190 / −0.320 | +0.190 | +0.401 |
| 315 – 400 | +0.089 / 0 | −0.210 / −0.350 | +0.210 | +0.439 |
| 400 – 500 | +0.097 / 0 | −0.230 / −0.385 | +0.230 | +0.482 |
Deviations in mm at the upper end of each range; negative clearance = interference. Clearance columns are shown on wider screens. Sub-ranges (e.g. 18–24 / 24–30) can differ for r, s, t, u, v, x, y, z — use the calculator for the exact size. “—” means ISO 286 doesn't define this class below that size (e.g. t only starts at 24 mm).
Is H8/d9 a clearance fit?
Yes — H8/d9 is a clearance fit per ISO 286 (see types of fits). At Ø25 mm it gives a clearance of 0.065 mm to 0.150 mm mm, depending which parts of the tolerance zones are paired.
What is the H8/d9 tolerance at 25 mm?
At a nominal size of Ø25 mm, H8 allows a hole diameter from 25.000 to 25.033 mm, and d9 allows a shaft diameter from 24.883 to 24.935 mm.